From 07ff73a932b725b2a4675bd0cc1a86b4933e433e Mon Sep 17 00:00:00 2001 From: Tero Kristo Date: Mon, 30 Nov 2015 16:43:25 +0200 Subject: clk: ti: omap5+: dpll: implement errata i810 Errata i810 states that DPLL controller can get stuck while transitioning to a power saving state, while its M/N ratio is being re-programmed. As a workaround, before re-programming the M/N ratio, SW has to ensure the DPLL cannot start an idle state transition. SW can disable DPLL idling by setting the DPLL AUTO_DPLL_MODE=0 or keeping a clock request active by setting a dependent clock domain in SW_WKUP. This errata impacts OMAP5 and DRA7 chips, so enable the errata for these. Signed-off-by: Tero Kristo Signed-off-by: Stephen Boyd --- drivers/clk/ti/dpll3xxx.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) (limited to 'drivers/clk/ti') diff --git a/drivers/clk/ti/dpll3xxx.c b/drivers/clk/ti/dpll3xxx.c index f4dec00fb684..1c300388782b 100644 --- a/drivers/clk/ti/dpll3xxx.c +++ b/drivers/clk/ti/dpll3xxx.c @@ -305,8 +305,9 @@ static void _lookup_sddiv(struct clk_hw_omap *clk, u8 *sd_div, u16 m, u8 n) static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 freqsel) { struct dpll_data *dd = clk->dpll_data; - u8 dco, sd_div; + u8 dco, sd_div, ai = 0; u32 v; + bool errata_i810; /* 3430 ES2 TRM: 4.7.6.9 DPLL Programming Sequence */ _omap3_noncore_dpll_bypass(clk); @@ -350,6 +351,25 @@ static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 freqsel) v |= sd_div << __ffs(dd->sddiv_mask); } + /* + * Errata i810 - DPLL controller can get stuck while transitioning + * to a power saving state. Software must ensure the DPLL can not + * transition to a low power state while changing M/N values. + * Easiest way to accomplish this is to prevent DPLL autoidle + * before doing the M/N re-program. + */ + errata_i810 = ti_clk_get_features()->flags & TI_CLK_ERRATA_I810; + + if (errata_i810) { + ai = omap3_dpll_autoidle_read(clk); + if (ai) { + omap3_dpll_deny_idle(clk); + + /* OCP barrier */ + omap3_dpll_autoidle_read(clk); + } + } + ti_clk_ll_ops->clk_writel(v, dd->mult_div1_reg); /* Set 4X multiplier and low-power mode */ @@ -379,6 +399,9 @@ static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 freqsel) _omap3_noncore_dpll_lock(clk); + if (errata_i810 && ai) + omap3_dpll_allow_idle(clk); + return 0; } -- cgit v1.2.3